In the high volume food service industry it is desirable to be able to quickly dispense a metered amount of fluid food product. Such is important not only in the fast food environment where the server must be able to quickly dispense accurate amounts of food product, but also in the self-service environment where the customer himself dispenses the fluid, for example, a hot fudge topping to a dish of ice cream.
In some prior dispensers of which we are aware, the food product is merely poured into a cavity which, if necessary, as in the case of dispensing hot fudge, cheese, syrup or the like, is heated. In other dispensers, a can of the food to be dispensed is positioned in a hot water bath and heated thereby. In both instances the fluid may be dispensed by the use of a hand operated pump. However, such operation is not always desirable, particularly in the self-service situations, because the user may use his own discretion as to the amount of product being dispensed. Moreover, such hand pump operation inevitably leaves a certain amount of wasted food undispensed, that is, the pumps will not fully deplete the container resulting in wasted food product.
To avoid at least some of these potentially economically disadvantageous effects, many dispensers are provided with sophisticated metering pumps which, when activated, dispense a precise amount of fluid. However, such pumps are quite costly and require frequent maintenance, thus adding significantly to the cost and efficiency of the dispensing unit.
Moreover, in all such dispensers, several deleterious "food zones" exist, that is, locations where the food product comes into contact with the mechanisms of the dispenser. Thus, the law requires that all of these food zones, such as the cavity, the pump and the like, must be frequently cleaned to assure the sanitary nature of the dispenser. However, both the hand pumps and the sophisticated metering pumps are quite difficult to clean requiring a great deal of time and effort on the part of the user and the resulting downtime of the dispenser.
In an attempt to eliminate such food zones, some dispensers, such as shown in U.S. Pat. Nos. 4,513,885 and 4,690,307, dispense the fluid food product from a plastic bag through a relatively long tube attached thereto. Through a hand operated peristaltic pumping action, a plurality of rollers squeeze the tube to draw fluid from the bag on one side of the rollers and discharge fluid from the tube on the other side of the rollers. While solving some of the food zone problems discussed above, such a peristaltic system does not eliminate the problems associated with hand pumps having a number of movable parts, nor does it provide a positive shut-off for the food product about to be dispensed from the other side of the rollers. Thus, that food product can, and will be, exposed to air and the bacteria associated therewith while awaiting to be dispensed by the next hand pump operation. Moreover, it would be difficult, if not impossible, to uniformly heat both the bag and the tube if the dispensing of hot fluids were desired. Similarly, any electrical equipment associated with such heating, or with automating the hand operation, would of necessity not be self-containable in a separate unit and thus would render cleaning and maintenance of the device difficult and impractical.